Analyjis of ike Bath Waters. - ^03 



V. 



I . 

 AChemical Examination of the BatkWaters. Jiji George Smith Gibber, lyi.D.F.R.S. 



(Continued from p. 363.) 



V-^NE hundred and ten ounces,o^ the King's Bath water left after evaporation to dry- 

 nefs eighty grains of folid matter. I evaporated this, water in a new tin veflel, and I 

 found that the folid fubftance adhered ftron,gly to the fides pf the vefTel, I made ufe of 

 an ivory knife to detach this fubftance, and I obferved that the knife was thereby con- 

 fiderably abraded. This circumftance induced me to examine very particularly this 

 nature of the produfts, and I found that a targe proportion remained infoluble after I 

 had fubjefted them- to fhe aftion of th,e three ftrong mineral acids. To this infoluble 

 fubftance, I added above a thoufand times its^ quantity of diftilled water; ftill I per- 

 ceived that it remained unchanged. Th^s precipitate defcended rapidly to the bottom of 

 the vefl'el, I feparated it by a filtre from the water, and I fpjtinli it to pofTcTs no falirie 

 or earthy tafte. '• , 



In order to procure a larger quantity of this fuljftance, I evaporated 168 ounces of 

 the King's Bath water nearly to dryness. On this refiduuin I poured a confiderablc 

 qua'ntity of nitric acid, and I left it tp ftand for above an hour, I then added a large 

 quantity of boiling water, from which a white precipitate, fell rapidly to the bottom 

 of the veflel. I filtered the liquor, and I, found, after carefully drying the fubftance 

 left on the filtre, that it weighed twenty grains. J The oxalic acid .does not decompofe 

 it, neither was its quantity diminifhed by boiling it a c<;J9Aderable, time in diftilled 

 water. 



Profeflbr Bergman obferves, in his Analyfis of Mineral "W'4ters,"tliat the portion, 

 when the other ingredients are feparated, which refifts the aftion of a fufScient quantity 

 of marine acid is filicious earth, which may be farther determined by the blow-pipe ; 

 for this earth, when added to the mineral alkali in fufion, unites with it "with a violent 

 eflervefcence, and is thereby totally diflblved. ', , 



Mr. Kirwan fays, that the general method of difcpverbg the, filicious earth, is to 

 evaporate a large, quantity of water nearly to drynels, then to fuperfaturate and re- 

 diffolve all that may have been precipitated by adding a fufficiency of nitrous or vitriolic 

 acids, and then evaporate to drynefs. If then the dry mafs be once more re-diflblved 

 in water, and filtered, the filicious earth will remain on the filtre. It is diftinguiflied by 

 its infolubility in moft acids, and its vitrefcibility with two parts foda. 



I expofed fix grains of this fubftance mixed with double its weight of focft, in a fmall 

 platina crucible to a very ftrong heat which 1 urged with a pair of double bellows, and 



I found 



